A series of acyl fluorides was synthesized at 100 mmol scale using phase-transfer-catalyzed
halogen exchange between acyl chlorides and aqueous bifluoride solution. The convenient
procedure consists of vigorous stirring of the biphasic mixture at room temperature,
followed by extraction and distillation. Isolated acyl fluorides (usually 7–20 g)
display excellent purity and can be transformed into sterically hindered amides and
esters when treated with lithium amide bases and alkoxides under mild conditions.
Key words
acyl fluorides - phase-transfer catalysis - directed
ortho-metalation - amides - esters